Why not think of it as one that was cut down by a gunsmith in Dodge City or someplace? As has been stated, some were cut down.
IMHO, it's part of "the experience" to know what was real and not with regards to bp. I have a 5.5 inch Remmie like in the photo above. I also have one with checkered grips, color case hardened frame, and a fully fluted cylinder. Now THAT is really a total fantasy-land gun, but I like it a lot. The flutes are a cool addition and the checker ing makes it grip well.
Were I to use it in some western video production I could make up some interesting back story to justify it's existance.
I have watched A LOT of old cowboy movies and TV westerns over time....have many of 'em on DVD. Some recent productions have gotten fairly good historically (though the stories may be fictional) but westerns from the 1950s-1970s were pretty well just imagination. There was no Paladin, no Lone Ranger, no actual Cartwrights. A character portrayed by actor Rory Calhoun in
THE TEXAN was a real person, but Calhoun's version was a hero, the real one was a murderous scoundrel. Errol Flynn portrayed General Custer in
THEY DIED WITH THEIR BOOTS ON, which was an interesting movie, but historic bunk.
There's no reason to disdain these fantasy guns if you like them. You don't have to .... I mean, it's your choice.
But if you like a little fun in life....why not?